The present invention relates to an arrangement of nanomaterials which act as a substrate for a surface-enhanced Raman scattering. A method of Raman scattering and a method of manufacturing the substrate are also disclosed. The substrate comprises a plurality of nanostructures, for example nanowires, and metal nanoparticles are arranged on the surface of the nanostructures. The metal nanoparticles are of a material selected from the group comprising Au, Ag, Cu, Fe, Co, Ni, Ru, Rh, Pd, Pt or an alloy. This nano-on-nano arrangement increase the surface area and provides a significant increase in detection sensitivity. A substrate comprising a nanomaterial substrate form of a plurality of nanostructure of a noble metal and noble metal nanoparticles of a different material on the surface of said nanostructure is also disclosed.